Este mapa muestra las anomalías globales de temperatura para julio de 2023, según el análisis GISTEMP realizado por investigadores del Instituto Goddard de Estudios Espaciales de la NASA. Las anomalías de temperatura reflejan la comparación de julio de 2023 con la temperatura media para el mes de julio entre 1951 y 1980. Credits: Instituto Goddard de Estudios Espaciales de la NASA
Según los investigadores del Instituto Goddard de Estudios Espaciales (GISS, por sus siglas en inglés) de la NASA, en Nueva York, julio de 2023 fue el mes más caluroso de todos los que se han registrado en el registro de temperaturas mundiales.
“Desde su primer día [en la oficina], el presidente Biden ha tratado la crisis climática como la amenaza existencial de nuestro tiempo”, ha declarado Ali Zaidi, asesor nacional de la Casa Blanca en materia de clima. “Con el telón de fondo de las altas temperaturas, los incendios forestales y las inundaciones sin precedentes, el análisis de la NASA pone en contexto la urgencia del liderazgo sin precedentes del presidente Biden en materia de clima”. Desde la aprobación de la Ley de Reducción de la Inflación, la mayor inversión climática de la historia, hasta la invocación de la Ley de Producción de Defensa para impulsar la producción nacional de energía limpia, pasando por el refuerzo de la resistencia climática en comunidades de todo el país, el presidente Biden está cumpliendo la agenda climática más ambiciosa de la historia”.
En su conjunto, julio de 2023 fue 1,1 grados centígrados (2,09 F) más cálido que el julio promedio entre 1951 y 1980. El análisis de GISS se centra principalmente en los cambios de temperatura a largo plazo durante décadas y siglos, y un periodo base fijo produce anomalías coherentes a lo largo del tiempo. Las temperaturas “normales” se definen por varias décadas o más, normalmente 30 años.
“Los datos de la NASA confirman lo que miles de millones de personas en todo el mundo, literalmente, han sentido: las temperaturas de julio de 2023 lo convirtieron en el mes más caluroso que se haya registrado. En cada rincón del país, los estadounidenses están experimentando de primera mano los efectos del cambio climático, lo que subraya la urgencia de la histórica agenda climática del presidente Biden”, dijo el administrador de la NASA, Bill Nelson. “La ciencia es clara. Debemos actuar ahora para proteger nuestro planeta; es el único que tenemos”.
Este gráfico muestra las anomalías de la temperatura global para cada mes de julio desde la década de 1880, según el análisis GISTEMP de la NASA. Las anomalías reflejan en qué medida la temperatura global estuvo por encima o por debajo de la norma de 1951-1980 para el mes de julio.Credits: Instituto Goddard de Estudios Espaciales de la NASA / Observatorio de la Tierra de la NASA
Algunos lugares de Sudamérica, África del Norte, América del Norte y la Península Antártica han sido especialmente calurosos y experimentaron aumentos de temperatura de unos cuatro grados centígrados (7,2 grados Fahrenheit). En general, el calor extremo de este verano ha puesto bajo alertas térmicas a decenas de millones de personas y se ha vinculado a cientos de enfermedades y muertes relacionadas con el calor. El récord de julio continúa una tendencia a largo plazo de calentamiento causado por las actividades humanas e impulsado principalmente por las emisiones de gases de efecto invernadero que se ha hecho evidente en las últimas cuatro décadas. Según datos de la NASA, los cinco julios más calurosos desde 1880 se han producido en los últimos cinco años.
“El cambio climático está afectando a la gente y a los ecosistemas de todo el mundo, y esperamos que muchos de estos impactos se intensifiquen con el calentamiento continuado”, dijo Katherine Calvin, científica jefe y asesora principal sobre el clima en la sede de la NASA en Washington. “Nuestra agencia observa el cambio climático, sus impactos y sus agentes impulsores, como los gases de efecto invernadero, y nos comprometemos a proporcionar esta información para ayudar a la gente a planificar el futuro.”
La NASA elabora su registro de temperaturas a partir de datos sobre la temperatura del aire en superficie procedentes de decenas de miles de estaciones meteorológicas, así como de datos sobre la temperatura de la superficie del mar obtenidos por instrumentos instalados en barcos y boyas. Estos datos en bruto se analizan mediante métodos que tienen en cuenta el espaciado variable de las estaciones de temperatura en el planeta y los efectos del calentamiento urbano que podrían sesgar los cálculos.
“Este mes de julio no sólo ha sido más cálido que los otros meses de julio anteriores, sino que ha sido el mes más cálido de todos nuestros registros, que se remontan a 1880”, declaró Gavin Schmidt, director del GISS. “La ciencia deja claro que esto no es normal. El alarmante calentamiento del planeta se debe principalmente a las emisiones de gases de efecto invernadero de origen humano. Y ese aumento de las temperaturas medias está impulsando el peligroso calor extremo que la gente está experimentando aquí y en todo el mundo.”
Las altas temperaturas de la superficie del mar contribuyeron al récord de calor de julio. El análisis de la NASA muestra temperaturas oceánicas especialmente cálidas en el Pacífico tropical oriental, lo que evidencia el fenómeno de El Niño que comenzó a desarrollarse en mayo de 2023. Fenómenos como El Niño o La Niña, que calientan o enfrían el Océano Pacífico tropical, pueden contribuir en pequeña medida a la variabilidad interanual de las temperaturas globales. Sin embargo, estas contribuciones no suelen notarse cuando El Niño comienza a desarrollarse en el verano del hemisferio norte. La NASA espera ver los mayores impactos de El Niño en febrero, marzo y abril de 2024.
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Workers who are in frequent contact with potentially sick animals are at high risk of bird flu infection.
Costfoto/NurPhoto via Getty ImagesRon Barrett, Macalester College
Disease forecasts are like weather forecasts: We cannot predict the finer details of a particular outbreak or a particular storm, but we can often identify when these threats are emerging and prepare accordingly.
The viruses that cause avian influenza are potential threats to global health. Recent animal outbreaks from a subtype called H5N1 have been especially troubling to scientists. Although human infections from H5N1 have been relatively rare, there have been a little more than 900 known cases globally since 2003 – nearly 50% of these cases have been fatal – a mortality rate about 20 times higher than that of the 1918 flu pandemic. If the worst of these rare infections ever became common among people, the results could be devastating.
Approaching potential disease threats from an anthropological perspective, my colleagues and I recently published a book called “Emerging Infections: Three Epidemiological Transitions from Prehistory to the Present” to examine the ways human behaviors have shaped the evolution of infectious diseases, beginning with their first major emergence in the Neolithic period and continuing for 10,000 years to the present day.
Viewed from this deep time perspective, it becomes evident that H5N1 is displaying a common pattern of stepwise invasion from animal to human populations. Like many emerging viruses, H5N1 is making incremental evolutionary changes that could allow it to transmit between people. The periods between these evolutionary steps present opportunities to slow this process and possibly avert a global disaster.
Spillover and viral chatter
When a disease-causing pathogen such as a flu virus is already adapted to infect a particular animal species, it may eventually evolve the ability to infect a new species, such as humans, through a process called spillover.
Spillover is a tricky enterprise. To be successful, the pathogen must have the right set of molecular “keys” compatible with the host’s molecular “locks” so it can break in and out of host cells and hijack their replication machinery. Because these locks often vary between species, the pathogen may have to try many different keys before it can infect an entirely new host species. For instance, the keys a virus successfully uses to infect chickens and ducks may not work on cattle and humans. And because new keys can be made only through random mutation, the odds of obtaining all the right ones are very slim.
Given these evolutionary challenges, it is not surprising that pathogens often get stuck partway into the spillover process. A new variant of the pathogen might be transmissible from an animal only to a person who is either more susceptible due to preexisting illness or more likely to be infected because of extended exposure to the pathogen.
Even then, the pathogen might not be able to break out of its human host and transmit to another person. This is the current situation with H5N1. For the past year, there have been many animal outbreaks in a variety of wild and domestic animals, especially among birds and cattle. But there have also been a small number of human cases, most of which have occurred among poultry and dairy workers who worked closely with large numbers of infected animals.
Pathogen transmission can be modeled in three stages. In Stage 1, the pathogen can be transmitted only between nonhuman animals. In stage 2, the pathogen can also be transmitted to humans, but it is not yet adapted for human-to-human transmission. In Stage 3, the pathogen is fully capable of human-to-human transmission.Ron Barrett, CC BY-SA
Epidemiologists call this situation viral chatter: when human infections occur only in small, sporadic outbreaks that appear like the chattering signals of coded radio communications – tiny bursts of unclear information that may add up to a very ominous message. In the case of viral chatter, the message would be a human pandemic.
Sporadic, individual cases of H5N1 among people suggest that human-to-human transmission may likely occur at some point. But even so, no one knows how long or how many steps it would take for this to happen.
Influenza viruses evolve rapidly. This is partly because two or more flu varieties can infect the same host simultaneously, allowing them to reshuffle their genetic material with one another to produce entirely new varieties.
Genetic reshuffling – aka antigenic shift – between a highly pathogenic strain of avian influenza and a strain of human influenza could create a new strain that’s even more infectious among people.Eunsun Yoo/Biomolecules & Therapeutics, CC BY-NC
These reshuffling events are more likely to occur when there is a diverse range of host species. So it is particularly concerning that H5N1 is known to have infected at least 450 different animal species. It may not be long before the viral chatter gives way to larger human epidemics.
Reshaping the trajectory
The good news is that people can take basic measures to slow down the evolution of H5N1 and potentially reduce the lethality of avian influenza should it ever become a common human infection. But governments and businesses will need to act.
People can start by taking better care of food animals. The total weight of the world’s poultry is greater than all wild bird species combined. So it is not surprising that the geography of most H5N1 outbreaks track more closely with large-scale housing and international transfers of live poultry than with the nesting and migration patterns of wild aquatic birds. Reducing these agricultural practices could help curb the evolution and spread of H5N1.
Large-scale commercial transport of domesticated animals is associated with the evolution and spread of new influenza varieties.ben/Flickr, CC BY-SA
People can also take better care of themselves. At the individual level, most people can vaccinate against the common, seasonal influenza viruses that circulate every year. At first glance this practice may not seem connected to the emergence of avian influenza. But in addition to preventing seasonal illness, vaccination against common human varieties of the virus will reduce the odds of it mixing with avian varieties and giving them the traits they need for human-to-human transmission.
At the population level, societies can work together to improve nutrition and sanitation in the world’s poorest populations. History has shown that better nutrition increases overall resistance to new infections, and better sanitation reduces how much and how often people are exposed to new pathogens. And in today’s interconnected world, the disease problems of any society will eventually spread to every society.
For more than 10,000 years, human behaviors have shaped the evolutionary trajectories of infectious diseases. Knowing this, people can reshape these trajectories for the better.Ron Barrett, Professor of Anthropology, Macalester College
This article is republished from The Conversation under a Creative Commons license. Read the original article.
One of the most powerful objects in the universe is a radio quasar – a spinning black hole spraying out highly energetic particles. Come too close to one, and you’d get sucked in by its gravitational pull, or burn up from the intense heat surrounding it. But ironically, studying black holes and their jets can give researchers insight into where potentially habitable worlds might be in the universe.
As an astrophysicist, I’ve spent two decades modeling how black holes spin, how that creates jets, and how they affect the environment of space around them.
What are black holes?
Black holes are massive, astrophysical objects that use gravity to pull surrounding objects into them. Active black holes have a pancake-shaped structure around them called an accretion disk, which contains hot, electrically charged gas.
The plasma that makes up the accretion disk comes from farther out in the galaxy. When two galaxies collide and merge, gas is funneled into the central region of that merger. Some of that gas ends up getting close to the newly merged black hole and forms the accretion disk.
Black holes and their disks can rotate, and when they do, they drag space and time with them – a concept that’s mind-boggling and very hard to grasp conceptually. But black holes are important to study because they produce enormous amounts of energy that can influence galaxies.
How energetic a black hole is depends on different factors, such as the mass of the black hole, whether it rotates rapidly, and whether lots of material falls onto it. Mergers fuel the most energetic black holes, but not all black holes are fed by gas from a merger. In spiral galaxies, for example, less gas tends to fall into the center, and the central black hole tends to have less energy.
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One of the ways they generate energy is through what scientists call “jets” of highly energetic particles. A black hole can pull in magnetic fields and energetic particles surrounding it, and then as the black hole rotates, the magnetic fields twist into a jet that sprays out highly energetic particles.
Magnetic fields twist around the black hole as it rotates to store energy – kind of like when you pull and twist a rubber band. When you release the rubber band, it snaps forward. Similarly, the magnetic fields release their energy by producing these jets.
The accretion disk around a black hole can form a jet of hot, energetic particles surrounded by magnetic field lines. NASA, ESA, and A. Feild (STScI), CC BY
These jets can speed up or suppress the formation of stars in a galaxy, depending on how the energy is released into the black hole’s host galaxy.
Rotating black holes
Some black holes, however, rotate in a different direction than the accretion disk around them. This phenomenon is called counterrotation, and some studies my colleagues and I have conducted suggest that it’s a key feature governing the behavior of one of the most powerful kinds of objects in the universe: the radio quasar.
You can imagine the black hole as a rotating sphere, and the accretion disk as a disk with a hole in the center. The black hole sits in that center hole and rotates one way, while the accretion disk rotates the other way.
This counterrotation forces the black hole to spin down and eventually up again in the other direction, called corotation. Imagine a basketball that spins one way, but you keep tapping it to rotate in the other. The tapping will spin the basketball down. If you continue to tap in the opposite direction, it will eventually spin up and rotate in the other direction. The accretion disk does the same thing.
Since the jets tap into the black hole’s rotational energy, they are powerful only when the black hole is spinning rapidly. The change from counterrotation to corotation takes at least 100 million years. Many initially counterrotating black holes take billions of years to become rapidly spinning corotating black holes.
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So, these black holes would produce powerful jets both early and later in their lifetimes, with an interlude in the middle where the jets are either weak or nonexistent.
When the black hole spins in counterrotation with respect to its accretion disk, that motion produces strong jets that push molecules in the surrounding gas close together, which leads to the formation of stars.
But later, in corotation, the jet tilts. This tilt makes it so that the jet impinges directly on the gas, heating it up and inhibiting star formation. In addition to that, the jet also sprays X-rays across the galaxy. Cosmic X-rays are bad for life because they can harm organic tissue.
For life to thrive, it most likely needs a planet with a habitable ecosystem, and clouds of hot gas saturated with X-rays don’t contain such planets. So, astronomers can instead look for galaxies without a tilted jet coming from its black hole. This idea is key to understanding where intelligence could potentially have emerged and matured in the universe.
Black holes as a guide
By early 2022, I had built a black hole model to use as a guide. It could point out environments with the right kind of black holes to produce the greatest number of planets without spraying them with X-rays. Life in such environments could emerge to its full potential. https://www.youtube.com/embed/b7mTVX9IE0s?wmode=transparent&start=0 Looking at black holes and their role in star formation could help scientists predict when and where life was most likely to form.
Where are such conditions present? The answer is low-density environments where galaxies had merged about 11 billion years ago.
These environments had black holes whose powerful jets enhanced the rate of star formation, but they never experienced a bout of tilted jets in corotation. In short, my model suggested that theoretically, the most advanced extraterrestrial civilization would have likely emerged on the cosmic scene far away and billions of years ago.
The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/
NASA’s SpaceX Crew-9 members pose together for a portrait inside the vestibule between the International Space Station and the SpaceX Dragon crew spacecraft. Clockwise from left, are NASA astronauts Butch Wilmore, Nick Hague, and Suni Williams, and Roscosmos cosmonaut Aleksandr Gorbunov. NASA
NASA is set to offer live coverage of the much-anticipated return of its SpaceX Crew-9 mission from the International Space Station (ISS). The event will commence with preparations for the Dragon spacecraft’s hatch closure at 10:45 p.m. EDT on Monday, March 17.
In a proactive move, NASA and SpaceX convened on Sunday to evaluate the weather and splashdown conditions off Florida’s coast in preparation for the Crew-9 mission return. Thanks to favorable weather forecasts for Tuesday evening, March 18, mission managers are targeting an earlier return opportunity. This adjustment serves to allow the onboard crew ample time to complete their handover duties while also providing operational flexibility in anticipation of less favorable weather later in the week.
The Crew-9 mission features NASA astronauts Nick Hague, Suni Williams, and Butch Wilmore, along with Roscosmos cosmonaut Aleksandr Gorbunov. These skilled astronauts have been conducting a long-duration science expedition aboard the ISS and will bring back critical time-sensitive research to Earth.
As the launch nears, mission managers will continue to monitor weather conditions, which will play a pivotal role in the undocking process. Factors such as spacecraft readiness, recovery team preparedness, and sea states will all influence the timing and location of the splashdown. NASA and SpaceX will finalize and communicate the specific splashdown site as the Crew-9 return approaches.
For those interested in following along, you can watch the Crew-9 return activities live on NASA+. Additional viewing options, including various social media platforms, are also available. Schedule information can be found at NASA Live.
Here’s a timeline of the upcoming live coverage (all times EDT and subject to change):
Monday, March 17
10:45 p.m. – Hatch closing coverage begins on NASA+
Tuesday, March 18
12:45 a.m. – Undocking coverage begins on NASA+
1:05 a.m. – Undocking
Following the undocking coverage, there will be an audio-only feed. Assuming favorable weather conditions at the splashdown sites, continuous coverage will resume on NASA+ before the deorbit burn.
4:45 p.m. – Return coverage begins on NASA+
5:11 p.m. – Deorbit burn (approximate time)
5:57 p.m. – Splashdown (approximate time)
Following the splashdown, there will be a Return-to-Earth media conference at 7:30 p.m. on NASA+, featuring key participants, including:
Joel Montalbano, Deputy Associate Administrator, NASA’s Space Operations Mission Directorate
Steve Stich, Manager, NASA’s Commercial Crew Program
Jeff Arend, Manager for Systems Engineering and Integration, NASA’s International Space Station Office
Sarah Walker, Director, Dragon Mission Management, SpaceX
Mark your calendars and prepare to witness this exciting milestone in space exploration as NASA’s Crew-9 mission returns home!
Find full mission coverage, NASA’s commercial crew blog, and more information about the Crew-9 mission at:
The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/
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Este gráfico muestra las anomalías de la temperatura global para cada mes de julio desde la década de 1880, según el análisis GISTEMP de la NASA. Las anomalías reflejan en qué medida la temperatura global estuvo por encima o por debajo de la norma de 1951-1980 para el mes de julio.Credits: Instituto Goddard de Estudios Espaciales de la NASA / Observatorio de la Tierra de la NASA
Ron Barrett, Professor of Anthropology, Macalester College
This article is republished from The Conversation under a Creative Commons license. Read the original article.
